Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by IC engines. Generally exhaust gas aftertreatment systems comprise any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust gas aftertreatment systems for diesel-powered IC engines comprise a selective catalytic reduction (SCR) system, including a catalyst formulated to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3). Generally in such aftertreatment systems, an exhaust reductant (e.g., a diesel exhaust fluid such as urea) is injected into the SCR system to provide a source of ammonia and mixed with the exhaust gas to partially reduce the NOx gases. The reduction byproducts of the exhaust gas are then fluidly communicated to the catalyst included in the SCR system to decompose substantially all of the NOx gases into relatively harmless byproducts that are expelled out of the aftertreatment system.
Aftertreatment systems generally include a reductant insertion assembly for inserting a reductant into the SCR system. Conventional reductant insertion assemblies generally include one or more pumps with motors and/or other moving parts to pressurize and deliver the reductant to the SCR system. The reductant can form deposits in the pumps and may cause corrosion in the pump causing increased pump failure rates, limited flow rates, and frequent maintenance, thereby raising maintenance costs. Furthermore, when an engine associated with the aftertreatment system is turned OFF, reductant may remain in one or more reductant delivery lines, pumps, injectors, etc., and form reductant deposit, leading to more frequent maintenance and higher maintenance costs.